It is necessary during the manufacture of metallic spectacle frames to choose both the design and also the material in such a manner that the finished spectacle frame has the very highest degree of strength and is not deformed during practical use. Deformation of the spectacle frame can occur both in the area of the frame for the glasses and also in the area of the bows and always has the result that the spectacle no longer fits correctly and the user tries to bend the spectacle back into its original shape.
In order to prevent such deformation of the spectacle frame, various alloys have been developed and which are described, for example, in the DE-OS 26 26 251 and DE-OS 38 34 186.
The known alloys have the disadvantage that they are not suited or are only suited to a limited degree to meet certain demands since the material does not have a sufficient strength or resilient characteristics or loses strength during the manufacturing process, for example, during soldering or welding operations. A further disadvantage of the known alloys is that they have a very high nickel content. Since the percentage of population having allergies against nickel is significantly increased, many of these alloys cannot be used or can only be used at considerable expense, for example, by applying additional coatings. Additional disadvantages of the known alloys are caused by their relatively high price.
Connecting wires for electronic component parts must have a low electric conductivity and thus must have a low heat conductivity in order to achieve a protection against destructive temperatures for the electronic component parts during connecting operations, as for example during soldering.
The basic purpose of the invention is to provide an alloy for spectacles or connecting wires which, while being inexpensive to manufacture and having a high mechanical strength, has a low nickel content and a low heat conductivity.
The purpose is attained according to the invention by an alloy which, in percentage by weight, has the
following components: 63-78% copper, 3-7% nickel, 1-3% iron, 0.01-0.20% phosphorus, the remainder being zinc.
The alloy of the invention is distinguished by a number of significant advantages. In contrast to the alloys known from the state of the art, the alloy of the invention has a very low nickel content of only 3-7%, while the alloy described in DE-OS 26 26 251 can have a nickel content of up to 26%, similar to the alloy of DE-OS 38 34 186, which provides a nickel content of 17-25%.
A further, significant advantage of the alloy of the invention is that same has a higher recrystallization temperature than the presently known spectacle alloys. Thus, it is possible to weld or solder the alloy without noticeably influencing the elastic characteristics. The resilient behavior of the alloy, which is of a great importance, in particular in the case of spectacle bows, thus continues to exist also in the welding or soldering areas. Such critical areas are in particular those where the spectacle bow is connected to the hinge part. Common alloys have the tendency to loose strength in this connecting area with the result that the spectacle frame bends easily during practical use.
Furthermore, the alloy of the invention can be easier polished thus enhancing the total appearance of the spectacle frame.
The alloy of the invention is also distinguished by a better optical appearance and has thereby in particular a golden effect so that a thinner layer is needed when a gold coating is applied.
The alloy of the invention has fantastic spring characteristics, the iron and phosphorus content resulting in an increased strength compared with the presently known alloys.